Fluid retarder system



INVENTOR.

ATTORNEYS June 30, 1964 A. w. SIEVING FLUID RETARDER SYSTEM Filed April 6, 1961 ALFRED W S/EV/NG United States Patent 6) 3,139,158 FLUID RETARDER- SYSTEM AifredW. Sieving, Decatur, IlL, assignor to Caterpillar Tractor Co., Peoria, Ill., a corporation of California Filed Apr. 6, 1961, Ser. No. 101,230 4 Claims. (Cl. 18890) This invention relates to fluid retarder systems of the kind employed in vehicles to retard speed without excessive use of the conventional friction brakes- The inventionisparticularly direeted to the load cylinder andreservoir of such a system, together with venting and valving associated therewithto obtain positive and efiicient operation.

One of the'objects of -the invention is the provision of a combined load cylinder and reservoir that is not damaged beyond'an operable condition when it is dented by rocks or the like encountered in the operation of a large trucks and earthmoving machines;

Another object of the invention is to provide a system with adequate venting at all desirable points in its fluid circuits and with means for quickly and automatically closing the vents upon introduction of pressure to the circuit.

Further and more specific objects and advantages of the invention are made apparent in the following specification wherein the invention is described by reference to the accompanying drawing.

The drawing is a schematic view of a retarder system with parts illustrated in section to facilitate an understanding of their operation.

A retarder generally indicated at is of conventional form having a vaned rotor 11 fixed to a shaft 12 which may represent the drive shaft of a vehicle or any shaft coupled with the driving wheels. A vaned stator 13 is arranged in opposition to the rotor 11 and both are enclosed in a housing 14 which in the present case is illustrated as secured to a transmission housing, a portion of which is shown at 15. The retarder 10 operates in the usual manner being charged with oil, the pressure of which may be varied to vary the retarding efiect on the speed of the vehicle. Operation of the rotor 11 tends to cast the oil centrifugally outwardly of the housing 14 and in effect to pump it through a line 16, a heat exchanger 17 and a return line 18 to dissipate the heat in the oil which results from the action of the retarder. Coolant lines 19 and 20 are shown as leading to and from the heat exchanger, the inner construction of which is conventional and these lines are in communication with a suitable source of coolant which is circulated through the heat exchanger.

A combined load cylinder and reservoir for supplying oil under pressure to the retarder is shown as contained in a generally cylindrical housing 22. The interior of the housing is divided by a wall 23 into an upper oil reservoir 24 for makeup oil, an intermediate reservoir 25 and a lower air chamber 26. The reservoir 25 and air chamber 26 are separated by a loosely fitting piston 27 guided by a rod 28 in a guide tube 29 mounted in the wall 23. A seal is formed by a flexible diaphragm 32 suitably secured as shown between the wall of the cylindrical housing 22 and a skirt portion 30 of the piston 27. A spring 31 under compression between the wall 23 and the piston 27 normally retains the piston in the extended position shown, and when air under pressure is admitted to the chamber 26 the piston is urged upwardly-against the force of the spring and oil with which the chamber 25 is filled ice The system is initially filled-with oilthrough a filler cap 34shownas located at thetop of the heat exchanger and in communication. with the oil circuit. The system should be filled somewhat short of the top ofthe makeup reservoir 24 and heat exchanger to provide room forexpansion. The system is illustrated. in the drawing under normal conditions before. the, introduction of air under pressurethereto and the top of. the makeup oil chamber 24 is .vented through a breatherfitting shownat 35. In this condition, the upper portion of the retarder housing is also vented through a line 36 communicating with the reservoir 24 and includinga check. valve. 37; The ball element of the check valve rests on a slotted base 38 but will, upon introduction ofpressure into the retarder housing, be urged upwardly. to prevent flow through the line 36 l The. air chamber 26 below the. piston 27 is also vented through a line40 and a double acting check valve 41. A vent port 42 in the valve 41 is open while a valve element 43 is held away from the port by a spring 44. Makeup oil from the reservoir 24 is free to flow into the reservoir 25 to insure the exclusion of air therefrom through a spring opened diaphragm valve 46.

In operation, air under pressure is introduced to the valve 41 through a line 47 by actuation of a suitable control valve not shown. The compressed air first closes the vent 42 by raising the valve element 43 and then simultaneously flows to the air chamber 26 and through a line 48 and check valve 49 to the oil valve 46 by way of a line 50. The air pressure closes the valve 46 so that upon upward movement of the piston due to the pressure of air in the chamber 26 it must force oil from the reservoir 25 through the line 33 to the retarder until the housing thereof is full and the desired pressure therein is established.

The retarder is rendered inefiective by actuating the control valve to release air pressure through the line 47, thus permitting the valve element 43 to return to the position shown to vent air from the chamber 26 through the line 40 and vent opening 42. When this occurs, the force of the spring 31 retracts the piston 27 which rapidly withdraws oil from the retarder housing leaving only a sufficient quantity to eiiect lubrication of its moving parts during its idle operation.

As it might be possible, during the rapid flow of oil from the retarder back into the reservoir 25, for oil to surge upwardly through the valve 46 and be lost through the breather fitting 35, the valve 46 is maintained closed through the greater part of the return movement of the piston under influence of the spring 31. This is accomplished by the check valve 49 which has a restricted orifice 52 in a valve element 53 which is normally held closed by a spring 54. The valve element 53 is opened by incoming air when the retarder is being charged with pressure and then returned to a closed position by its spring so that air pressure in the line 50, which holds the valve 46 in its closed position, is gradually released through the orifice 52 thus retaining the valve 46 closed momentarily while the action of the piston withdraws oil from the retarder.

I claim:

1. A combined load cylinder and reservoir for supplying oil to a fluid retarder comprising a cylindrical housing, a wall dividing said housing into an upper makeup reservoir and a lower pressure reservoir for oil, a normally open valve in said wall, a piston reciprocably mounted in said pressure reservoir, means to admit air under pressure against said piston, means to admit air to said valve for moving it to a closed position, a common air'vent for said piston and valve, and means actuated by comed in said pressure reservoir, means to admit air underpressure against said piston, means actuated by said air under pressure to close said normally open valve, means to conduct oil from the pressure reservoir to the retarder upon admission of such air, and spring means opposing movement of the pistonby such air, a vent line between the upper portion of the retarder and the top of the make.

up reservoir, and a check valve in said line closed by pressure in the retarder and open upon return of the piston by said spring means.

' 3. The structure defined in claim 2 including a breather fitting in the top'of said makeup reservoir.

4; A combined load cylinder and reservoir for supplying oil to a fluid retarder comprising a cylindrical housing,

' normally open valve, a spring for returning the piston a Wall dividing said housing into an upper makeup reservoir and a lower pressure reservoir for oil, a normally open valve in said wall, a piston reciprocably mounted in said pressure reservoir, means to admit air under pressure against said piston, means to conduct oil from the pressure reservoir to the retarder upon admission of such air, means actuated by said air under, pressure toclose said upon release of air pressure'to withdraw oil from the retarder, and means to eif ect delayed opening of said valve.

References Cited in the tile of this patent UNITED STATES PATENTS 2,058,063 COX Oct. 20, 1936 2,498,572 OLeary Feb. 21, 1950 2,748,899 Booth et al June 5, 1956 2,748,900 Booth et a1. June 5, 1956 2,750,009 Pohl June 12, 1956 2,889,013 Schneider June 2, 1959 Booth et a1. Dec. 9, 1960 

1. A COMBINED LOAD CYLINDER AND RESERVOIR FOR SUPPLYING OIL TO A FLUID RETARDER COMPRISING A CYLINDRICAL HOUSING, A WALL DIVIDING SAID HOUSING INTO AN UPPER MAKEUP RESERVOIR AND A LOWER PRESSURE RESERVOIR FOR OIL, A NORMALLY OPEN VALVE IN SAID WALL, A PISTON RECIPROCABLY MOUNTED IN SAID PRESSURE RESERVOIR, MEANS TO ADMIT AIR UNDER PRESSURE AGAINST SAID PISTON, MEANS TO ADMIT AIR TO SAID VALVE FOR MOVING IT TO A CLOSED POSITION, A COMMON AIR VENT FOR SAID PISTON AND VALVE, AND MEANS ACTUATED BY COMPRESSED AIR FOR SIMULTANEOUSLY CLOSING SAID VENT AND ADMITTING AIR TO THE PISTON AND THE VALVE WHEREBY OIL FROM THE PRESSURE RESERVOIR CAN BE DIRECTED TO THE RETARDER. 